Di-acylglycerides as oil structuring agents

Abstract

The current research aims to explore the oil structuring performance of di-acylglycerides using di-stearin (DS) oleogels, while their mechanical, thermal and structural properties were compared with mono-stearin (MS) and tri-stearin (TS) oleogels. DS was able to form gels at concentration above 0.15 M (10 wt%), which was higher than MS (0.07 M-2.9 wt%) but lower than TS (0.18 M-18 wt%). DS-oleogels exhibited a thermo-reversible behavior characterized with crossover of storage and loss modulus during cooling, similar to MS and TS gelation behavior. DS-oleogels exhibited three broad melting peaks at 22.0–31.7 ℃, 40.8–46.9 ℃, and 54.5–59.8 ℃, indicating the formation of α polymorph which transformed to β′ and β during melting. This polymorph assignment was confirmed by XRD, while the lamellar crystal layers were confirmed by TEM. DS showed relative frequency-independent behavior suggesting an ideally elastic-like material, similar to MS- and TS-oleogels. Interestingly, at low concentration DS exhibited similar hardness values as TS but lower than MS, however, at ≥ 0.22 M, DS and MS exhibit similar values. This behavior suggests that at low concentration intermolecular bonds, such as hydrogen bonds, play a critical role while at higher concentration, secondary network stabilization mechanism such as crowding and aggregation becomes the predominant force.